Research Provides Feedyard Emission Data

When the EPA issued a final ruling Dec. 18 that required the reporting of continuous air releases of ammonia

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When the EPA issued a final ruling Dec. 18 that required the reporting of continuous air releases of ammonia and hydrogen sulfide by large confined animal feeding operations (CAFOs) to local and state emergency management entities, it created more than a little heartburn for cattle feeders.

Until this ruling, EPA hadn’t required ag operations to report air emissions under the Comprehensive Environmental Response, Compensation and Liability Act of 1980 and Emergency Planning and Community Right-to-Know Act of 1986. But with the new EPA rule, it was determined the reporting was required under the 1986 act and operations falling within the guidelines must report emissions by Jan. 20, says Ben Weinheimer, Texas Cattle Feeders Association (TCFA) vice president.

The rule applies to operations that can emit 100 lbs. or more of ammonia or hydrogen sulfide during any 24-hour period, Weinheimer says. These operations now must report the emissions to state and local emergency responders.

But with the rule came no guidelines on how to gather that info or report it, and there were no officially adopted emission factors available. Weinheimer says the industry turned to researchers working on “Air Quality: Reducing Emissions from Cattle Feedlots and Dairies,” a federally funded project headed by John Sweeten, director of the Texas AgriLife Research and Extension Center at Amarillo.

The project researchers, who had been gathering emissions data from area feedlots for the past six years, were pulled together to determine the best way for feedyard operators to estimate their emissions and develop a worksheet for calculating emissions, Sweeten says.

“The EPA rule basically gave these livestock operations one month to report ongoing emissions that exceeded the thresholds,” says Ken Casey, AgriLife Research air quality engineer. “Needless to say, releasing the rule when they did, just before Christmas, without any advance notice and requiring reporting in the early new year, left the industry scrambling to get together a response, as well as give responsible guidance to their members.”

Ammonia results. “We needed to convey to EPA that no single number is adequate to represent a basis for an emission factor, because emissions vary with what the cattle are fed, with the season, and even with the time of day,” says Brent Auvermann, AgriLife Extension researcher. “We presented EPA and the cattle-feeding industry with a range of emission factors that we believe would represent most feedyards in our area.”

Research from this project has shown that emission rates for ammonia during winter months are about half those during summer months, according to Rick Todd with USDA-ARS in Bushland, TX.

“Texas Panhandle feeding operations with more than 1,000 cattle could exceed the 100 lbs./day reporting requirement,” Todd says. “But the negative environmental effects of ammonia that EPA is concerned about are most likely where ammonia mixes with urban air pollution, or when ammonia is removed from the atmosphere in rain and over-fertilizes sensitive ecosystems.”

He and Auvermann agree that on the High Plains, ammonia is more of a regional than a local environmental concern. “Ammonia doesn’t stay in the atmosphere very long in its gaseous form,” Auvermann says. “Unless it reacts with other gases to form fine particles, it’s gone from the air within a few hours to a few days. And we don’t see much of the fine particles around here that would suggest otherwise.”

Hydrogen sulfide results. Casey and David Parker, a researcher at West Texas A&M University in Canyon, TX, aggregated hydrogen sulfide field data for the reporting process. Their research shows emission rates for hydrogen sulfide are lower during dry weather conditions and higher in wet conditions. On average, they are three times lower than ammonia concentrations – approaching the minimum detection levels by sophisticated equipment.

“Hydrogen sulfide isn’t currently classified as a hazardous air pollutant by EPA; it’s primarily of local and of minor regional concern,” Casey says. “The regulation of hydrogen sulfide varies from state to state.”

Concentrations measured at the center of a commercial Panhandle feedyard were substantially below the Texas regulatory threshold for the property boundary during the majority of the two-year monitoring period, he says. And concentrations at the boundary were considerably less than those measured at the center of the yard.

“What these researchers have found is that both ammonia and hydrogen sulfide represent exceedingly low concentrations over relatively large emitting surfaces and long time scales,” Sweeten says. “The annual emission numbers can add up to the low threshold values of reporting that EPA just set, but they don’t reach levels of general public concern.”

Weinheimer says that, with the quick response of the research group, the National Cattlemen’s Beef Association was able to send out “reporting packets” to feedyards in early January and conduct a Webinar on Jan. 15 to explain the requirements to its members.-- Texas AgriLife Extension release